Accumulator



Feb. 14, 1950 J, K, DOUGLAS 2,497,491

ACCUMULATOR Filed June 25, 1945 JAMES K. DOUGLAS ATTORNEY Patented Feb. 14, 1950 ACCUMULATQB James K., Douglas, ..S.. horouwodJ ,asslepor to 'I hejOilgear Company;I Milwaukee Wis.; a corporation of Wisconsin aspiration June 25, 1945, serai No.. 601,516

(C1. lssw) 19 :Claims l This invention relates ,-to'acoumulators of .the type in which .moti-ve-.liquidis-kept .under pres-` sure a-.fiuid .tight vessel. .byeas compressed .trito they upper .part of the .vessel and in intimate contact with the surface.. e f the1iquid. The motive liquid is ordinarily o il, the gas is ordinarily compressed air ,and they Will be Vreferred .to hereinassuch lbutit is to be `.under stood that the inf vention is not limited .toianaccumulator in which oil is kept under .pressure by .compressed air,

The vaccumulator is charged bya pump which delivers oil thereto .until the .air vtherein vis com: pressed to such ,an extent that the-pressure ,in the accumulator reaches a predetermined Amaximum and then further delivery of oil is inter.- rupted `such as by means of a .pressure respOllSive valve 4or bythe pump automatically reducing vits displacement until .it .is .delivering iust .enough oil to maintain ,the maximum pressure substantially constant.

Ihe oil stored in an accumulator is ordinarily employed to .eifect operation of Aa hydraulic niotor or other device at .Speeds in excess of any speed that .would be `possible if the motor or other device were operated solely .by oildelivered directly theretoirom a :pump of ,the .same size `as the pump .which `charges the accumulator. yFor example, Voil stored .in .an accumulator is often employed to advance the l.piston o f a hydraulic motor at ,high speed ,on `a Working stroke at the end of which the piston is re.- tracted by the pump or Aby vother means .and ,the pump immediately starts to deliver oil tothe accumulator to .recharge it.. '.Ihe r`oil .exhausted from the motor flows to a reselVOr .from which the pump is supplied Withpil.

` When lcompressed air is .in intimate conta-ct with. the surface 40f Oil, airwill Vdissolve v.in the cil very quickly but it will penetrate-.only a short distance below the V surface of theoil. Conseoueptlv, the upper stratum of loil ina -uid pres--Y sure type .accumulator is ,2' ...solution .of -Oil and air and this .solution will be xreferred to as fsaturated oil although ,the oil may not be completely saturated With ldir.

As long .as the oilin 4the accumulator is static, the stratum of saturated oiliusulates .the oil therebelow against penetration .by .the air to ,any considerable extent but, when the accumulator is recharged after beingpartiallydisclidrged, `the oil in the accumulator l,becomes .turbulent which causes .the saturated oil to be vmixed with the other oil and .unsaturated oil to continually .risc to .the surface where additional air is dissolved in it so thatdll of theoil in .the accumulator ,is soonseturated.

Wpenoil thereafter delivered .from V.the-.accumulator to the motor, itis .incapable of. effect? ins .positive performance .of the .inotor ...for the' reason .that .the air .the oil makes the .oil very elastic. ,Forerauipla if arcciprocating hydraulic. clot ris .opera at high ,speedthroueh o g." n. distance .icy` .saturated .oil delivered thereto .from

accumulator and ity is. -fopsratedet o slower speed .solely iov oilfwdelivered .thereto .at `a speed not :be .as .the .elasticity of thecatllrated oil in the motor will causethe motor speed to vary ,excesfsjirclr response. to .chcpgosio .ipotorload,

Aitor the motor diociiorgesthe oil .into .atmospheric reservoir, Atiieau `in oil .tends .to form .into bubbles rise .to the .surface .of the .oil in lthe .the oil If `the `oil .remained .in the .reserroir ,for .a cop- Sidcrolole period .oi all. of the .eroessair thel oil .would into .the .atmosphere out the pump is drawing oil from the reservoir and deliveries it. to .the .accumulator at the same time that .the motor dischareiu :into the reservoir so .that the oil .supplied to the pumpcontaius sir epdrhlepca. Yis. very elastic..

As each pump cylinder opens to the pump discharge port, the elastic oil in the cylinder is suddenly .compressed lov the pressure ip the eccurnulator with the result that pump delivery is reduced. Conseguently, a Ylonger time is required Yfor the ,pump tcchoree the accumulator than would 'benecssary if the oilwere free. o f excess air.

As each pump cylinderopens to the pump in l take port', the compressed elastic oil in `the cylinder' suddenly expands. 4These sudden compressions and expansions of the oil in the pump` cylinders causes'violent vibrations and results in excessive noise. The vibrations damage the equipment and lthe noise is very annoying tothe operator and to otherpersons'in the vicinity.

'The present -inventionhas as an `object to provide an accumulator which will overcome the above mentioned disadvantages of the prior accumulatore,

According-tothe'inventignin tsgeneral aspect, an accumulator is provided with means for p reventing the surface of the oil Lin the accumulator from-being agitated to thereby prevent air froml entering `the F greater part o f the oiljin the acqumulator.

The invention is exemplied by the accumulators shownin the accompanying drawing in which the vieu/s are as 'follows Fig, 1 is a 4vieyv 4partly in elevation andpartly in section of an accumulator in which the 'in vention is embodied, the section being taken approrimatcly on the ,line Al-i lof, Fe- 2 and c portion ,of r the accumulator intermediate its ends hasloeepomittod ip. order ,toshowthc ,accumulator opla or scolo- .;Eia. iis asectiopal ,plan .view taken op o .liuc Z- of .Ele-...1.

Fig. 3 is a view similar to Fig. 1 but showing a different form of interior construction.

Fig. 4 is a sectional plan view taken on the line 4-4 of Fig. 3.

Each of the accumulators chosen for illustration has a cylindrical body section I, a dome shaped top section 2 and a bottom section 3 having a flange 4 upon its lower end for connection to a pipe 5 through which oil flows to and from the accumulator. Top section 2 and bottom section 3 are rigidly secured, as by welding, to opposite ends of body section I and form therewith a fluid tight vessel.

Large accumulators ordinarily have walls composed of several thicknesses of metal. That is, a large accumulator ordinarily consists of a plurality of fluid tight vessels arranged one within another with the walls thereof in intimate conta-ct but in order to simplify lthe drawing each wall has been shown as a single thickness of metal. It is to be understood, however, that the invention is in no way limited to the construction shown.

The cross-sectional area of vessel I-3 is divided into a plurality of vertical channels each of which has suflicient length and a sufficiently small cross-sectional area to prevent incoming oil from agitating the surface of the oil in the accumulator regardless of whether the accumulator is fully charged or has been discharged to its lower limit, it being understood that the accumulator is never fully discharged when it is in operation.

Various means may be employed to form the channels. As shown in Figs. 1 and 2, a plurality of channels 6 are formed by a set of separators 'I and a set of separators 8 arranged at right angles to each other.

One set of separators may extend across the vessel and the other set may consist of short sections welded or otherwise secured to the separators of the first set but, as shown, separators l extend across the vessel in one direction and have slots 9 extending downward from the upper edges thereof, separators 8 extend across the vessel at right angles to separators 'I and have slots I0 extending upward from the lower edges thereof, and the unslotted portion of each separator extends thru slots in the separators at right angles thereto so that the two sets are interlocked.

Channels may also be provided by a plurality of tubes I I arranged within vessel I-3 as indicated in Figs. 3 and 4, the spaces outside of tubes I I providing a plurality of additional channels I2.

Tubes II have been shown arranged close together and as being connected into a unit by welding the walls of adjacent tubes to each other at the Lipper and lower ends thereof as indicated at I3 in Fig. 4 but the tubes may be spaced farther apart and connected to each other by fins welded to adjacent tubes at the upper and lower ends thereof.

The channel forming means, such as plates 'I and 8 or tubes II, are arranged within body section I before one end or the other thereof is closed by connecting top section 2 or bottom section 3 thereto.

In order to prevent oil from flowing at high velocity directly into the channels immediately above pipe 5, a suitable baille is preferably arranged below and spaced from the lower ends of the channels to provide a chamber I4 in which the oil is diffused before entering the channels. The baille may be of any suitable construction but it has been shown as a spherical perforated plate l5 which is fixed in position in any suitable manner such as by welding it to the side wall of bottom section 3.

When oil is pumped into the accumulator through pipe '5, it flows through the perforations in baille I5 and is diffused in the oil in chamber I4 so that oil enters all of the channels at nearly the same rate, thereby preventing excessive turbulence in any of the channels.

The accumulator should be large enough to hold considerably more oil than is required to operate the motor or other device. For example, assuming that the level of the oil is at a line a-a when the accumulator is charged to the desired pressure, the level of oil should be a considerable distance above the bottom of the accumulator, as indicated by the line b-b, when enough oil has been discharged from the accumulator to operate the motor or other device.

The upper ends of the channels should extend to or above line a-a. Each channel should have such a small cross-sectional area that the oil therein can be turbulent for only a very short distance and the lower ends of the channels should extend far enough below line b-b to prevent incoming oil from agitating the stratum of saturated oil which extends downward a short distance below line b-b when oil first starts to enter the accumulator to recharge it.

Since the stratum of saturated oil is never agitated, the oil discharged from the accumulator to the motor or other device is substantially free of excess air and the difficulties encountered by use of an ordinary accumulator are avoided.

The.accumulatordescribed herein is susceptible of various modifications and is adapted to various uses without departing from the scope of the invention which is hereby claimed as follows:

l. An accumulator, comprising a fluid tight vessel adapted to contain a quantity of liquid and a compressed gas above said liquid and having an opening at its lower end for the flow of liquid to and from the interior of said vessel, and a plurality of channels arranged within said vessel to divide the cross-sectional area thereof into a plurality of passages each of which has suilicient length and a sufficiently small cross-sectional area to prevent the upper portion of the liquid in said vessel from being agitated by liquid entering said vessel thru said opening.

2. An accumulator, comprising a fiuid tight vessel adapted to contain a quantity of liquid and a compressed gas above said liquid and having an opening at its lower end for the ow of liquid to and from the interior of said vessel, a plurality of channels arranged within said vessel to divide the cross-sectional area thereof into a plurality of passages each of which has sufficient length and a suficiently small cross-sectional area to prevent the upper portion of the liquid in said vessel from being agitated by liquid entering said vessel thru said opening, and a baille arranged below and spaced from the lower ends of said channels to prevent high velocity flow of liquid into the channels in alinement with said opening.

3. An accumulator, comprising a fluid tight vessel adapted to contain a quantity of liquid and a compressed gas above said liquid and having an opening at its lower end for the flow of liquid to and from the interior of said vessel, a plurality of channels arranged within said vessel to divide the cross-sectional area thereof into a plurality ofv passages each of which has sufficient length and a sufficiently small cross-sectional area to prevent the upper portion of the liquid in said vessel from being agitated by liquid entering said vessel thru said opening, and a perforated plate arranged in a stationary position between and spaced from said opening and the lower ends of said channels to divide liquid entering said vessel into a plurality of small streams.

4. An accumulator, comprising a fluid tight Vessel adapted to contain a quantity of liquid and a compressed gas above said liquid and having an opening at its lower end for the iiow of liquid to and from the interior of said vessel, and channel forming means arranged within said Vessel intermediate the ends thereof and dividing the cross-sectional area of said vessel into a plurality of channels small enough to prevent liquid entering through said opening from causing liquid in said channels to become turbulent for more than a very short distance.

5. An accumulator, comprising a fluid tight vessel adapted to contain a quantity of liquid and a compressed gas above said liquid and having an opening at its lower end for the flow of liquid to and from the interior of said vessel, channel forming means arranged within said vessel inter-mediate the ends thereof and dividing the cross-sectional area of said vessel into a plurality of channels small enough to prevent liquid entering through said opening from causing liquid in said channels to become turbulent for more than a very short distance, and a baille arranged below and spaced from the lower ends of said channels to prevent high velocity ow of liquid into the channels in alinement With said opening.

6. An accumulator, comprising a uid tight vessel adapted to contain a quantity of liquid and a compressed gas above said liquid and having an opening at its lower end for the flow of liquid to and from the interior of said vessel, a first plurality of spaced apart separators arranged Within said vessel and extending across the interior thereof, and a second plurality of spaced apart separators arranged at right angles to said first separators and forming therewith and with the Wall of said Vessel a plurality of channels to prevent the upper portion of the liquid in said vessel from being agitated by liquid entering through said opening.

7. An accumulator, comprising a fluid tight vessel adapted to contain a quantity of liquid and a compressed gas above said liquid and having an opening at its lower end for the flow of liquid to and from the interior of said vessel, a first plurality of spaced apart separators arranged within said vessel and extending across the interior thereof, a second plurality of spaced apart separators arranged at right angles to said iirst separators and forming therewith and with the wall of said vessel a plurality of channels to prevent the upper portion of the liquid in said vessel from being agitated by liquid entering through vessel adapted to contain a quantity of liquid and a compressed gas above said liquid and having an opening at its lower end for the flow of liquid to and from the interior of said Vessel, a first plurality of spaced apart separators arranged within said vessel and extending across the interior thereof, a second plurality of spaced apart separators arranged at right angles to said iirst separators and forming therewith and with the wall of said vessel a plurality of channels to prevent the upper portion of the liquid in said vessel from being agitated by liquid entering through said opening, and a perforated plate arranged in a stationary position between and spaced from said opening and the lower ends of said separators to divide liquid entering said Vessel into a plurality of small streams.

9. An accumulator, comprising a fluid tight vessel adapted to contain a quantity of liquid and a compressed gas above said liquid and having an opening at its lower end for the flow of liquid to and from the interior of said vessel, and a plurality of tubes arranged within said Vessel to provide a plurality of channels small enough to prevent the upper portion of the liquid in said vessel from being agitated by liquid entering through said opening.

10. An accumulator, comprising a fluid tight vessel adapted to contain a quantity of liquid and a compressed gas above said liquid land having an opening at its lower end for the flow of liquid to and from the interior of said vessel, and a plurality of channels arranged within said vessel to divide the cross-sectional area thereof into a plurality of passages each of which has suiiicient length and a sufficiently small crosssectional area to prevent the upper portion of the liquid in said vessel from being agitated by liquid entering said vessel thru said opening, said vessel being of such capacity that the liquid contained therein when said accumulator is fully charged is in excess of requirements and said I channels being of such lengths that the upper said opening, and a baille arranged below and spaced from the lower ends of said separators to prevent high velocity ow of liquid into the channels in alinement with said opening.

8. An accumulator, comprising a fluid tight ends thereof extend above the surface of the liquid after said accumulator has been fully charged and the lower ends thereof extend below the surface of the liquid after a normal volume of liquid has been discharged from said accumulator.

JAMES K. DOUGLAS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 361,649 Rider Apr. 19, 1887 1,051,450 Rider Jan. 28, 1913 1,103,931 Bennett July 21, 1914 1,448,151 Reeves Mar. 13, 1923 1,647,757 Storey Nov. 1, 1927 2,343,560 Klein et al. Mar. 7, 1944 2,390,319 Overbeke Dec. 4, 1945 2,399,444 Mercier Apr. 30. 1946 

